1. Field of the Invention
The instant invention relates to a device which simultaneously signals a locomotive crew and car inspectors when a railroad car hand brake remains applied and air is supplied to the air brake system.
2. Description of the Prior Art
Hand brakes are manually operated mechanical brakes which are primarily used to hold a railroad car at rest when the car is detached from a train. A typical mechanical hand brake arrangement includes a gear sector which multiplies a manually applied input force from a hand operated brake wheel or lever. The output of the gear sector exerts a tension force on a rod which is attached to a bell crank. The force pivots the bell crank. A brake chain is attached to the bell crank and to the brake lever system of the car. When the bell crank pivots, the brake chain is tensioned and the brake lever system moves the car brake shoes against their respective car wheels. It applies a force similar to that obtained when the car air brakes are applied.
On some railroad cars, a single hand brake applies the brakes on both of the car trucks. On other cars, a hand brake applies the brakes to the wheels of only one truck. In the event that a hand brake is inadvertently left applied when a train leaves a terminal, and the car is empty, the brake shoe force may be sufficient to lock the wheels and cause them to slide as the car moves. This may produce a flat spot and a double flange contour on the wheel that can cause a derailment when the wheel encounters a switch. If the car is not empty and the wheels rotate with the brake applied, heat will cause the wheels to become damaged to the extent that they must be changed and the brake shoes will be destroyed if the hand brake remains applied for an extended period of time.
It is most difficult for a car inspector to determine that a railroad car hand brake is applied on a car equipped with a hand brake which operates on a single truck and/or on a car which uses composition brake shoes. This is because hand brakes operable on only one truck are more easily overlooked by car inspectors during inspection. Also, there is less friction between composition brake shoes and car wheels than between cast metal brake shoes and car wheels at very low speeds. Consequently, the composition brake shoe will not lock a wheel as readily as a cast metal brake shoe when a train is starting into motion and moving slowly past inspectors. Of course, a locked wheel indicates a hand brake is applied. Furthermore, a composition brake shoe produces little or no audible sound when applied to a revolving wheel tread, whereas a cast metal brake shoe produces a definite audible sound when applied to a revolving wheel tread, which indicates a brake is applied.
A common type of device which indicates a railroad car hand brake is applied is shown in U.S. Pat. No. 3,854,417. In this device, a mechanically operated flag provides a visual indication when a car hand brake is applied. In order for the device to be effective as a warning, train crew members, inspectors or others must be within a reasonable distance of the car to observe the displayed flags. An average train may consist of 150 cars with lengths exceeding 50 feet. Since cars in the middle of the train may be over a half-mile away from either the locomotive or the caboose, the train crew members could not observe the flags while on the train. At night, or in adverse weather, it is possible that car inspectors standing beside the car would also not observe the flags.
It is desirable to provide a warning device which simultaneously alerts a train crew in a train locomotive and inspectors alongside the train that a railroad car hand brake has inadvertently been left applied. Furthermore, it is desirable to provide an indicating device which operates when a train is stationary so that an applied hand brake can be released before a train departs from a terminal and before brake shoe or wheel damage occurs.
Federal regulations require that brake pipe leakage tests be conducted before a train departs from where it is originally made up and at designated distances along the route to its destination. The brake pipe is the length of pipe and hose extending throughout the length of the train by means of which compressed air is supplied to the brake devices on the railroad cars and the pressure so controlled as to effect the application and release of the brakes. The regulations state the brake pipe leakage must not exceed five pounds per minute. The brake pipe leakage test is performed by the crew of the locomotive which observes an air pressure gauge to determine if there is brake pipe leakage which exceeds five pounds per minute. The instant invention provides a signal device which is connected to the hand brake mechanism on a railroad car and which causes a brake pipe line to be opened such that brake pipe leakage exceeds five pounds per minute when the car hand brake is applied and air pressure is supplied to the brake pipe. In this way, the crew of the locomotive is made aware that a hand brake remains applied on a car in the train. Further, the instant signal device provides an audible whistle when the hand brake is applied and air pressure is supplied to the brake pipe. This enables car inspectors to quickly locate a car which has a set hand brake.